The present invention relates to an automatic weighing machine capable of automatically switching between a weighing mode and a counting mode for finding a combination of articles having a desired total weight or count.
There has been put to use an automatic weighing machine having a plurality of weighing machines or units for measuring the weights of articles charged in the weighing units. The measured weights are supplied to an arithmetic control unit comprising a microcomputer, for example, in which the measured weights are combined and the weight combinations are compared with a preset weight value to find an optimum combination of weights which is equal to the preset weight value or closet to the preset weight value within the range between upper and lower weight limits. The articles are then discharegd from those weighing units which are selected as giving the optimum combination of weights.
Another known automatic weighing machine operates by measuring the weights of the articles charged in the weighing units, and supplying the measured weights to the arithmetic control unit. The arithmetic control unit then divides the weights by the average weight of an article (hereinafter referred to as a "unit weight") to compute the number or counts of the articles. The counts are then combined and the count combinations are compared with a preset count to find an optimum combination of counts which is equal to the preset count or closet to the preset count within the range between upper and lower count limits. The articles are then discharged from those weighing units which are selected as giving the optimum combination of counts. The automatic weighing machine employing the above counting process updates the unit weight each time the weighing cycle is completed, thereby increasing the accuracy of weighing.
The assigne of the subject application has filed Japanese Patent Application No. 57-231652 disclosing an automatic weighing machine in which one of weighing and counting modes is selected dependent on the articles charged in the weighing units, and a combination of articles is found and discharged which gives an optimum combination of weights or counts.
With the conventional automatic weighing machines having such two selectable modes, the switching between the weighing and counting modes is effected manually by a selector switch. The manual operation of the selector switch is disadvantageous in that it is tedious to operate the switch, and mode switching is not reliable because the operator may forget to operate the switch. Further, the process in the counting mode is time-consuming since the unit weight is updated each time the weighing cycle is completed.